Denial-of-Service Attacks Continue to Grow in Sophistication, Capacity

Large-packet and reflection attacks ratchet up the bandwidth of denial-of-service in the first three months of 2014, according to a report from Web security firm Incapsula.

Massive distributed denial-of-service attacks using infrastructure servers to amplify floods of data have garnered much attention in the past year. But other attack techniques using a more basic network packet account for the majority of large-volume DDoS attacks, according to a report published by Internet-security firm Incapsula.

In the 2013-2014 DDoS Threat Landscape Report, published on March 27, the security firm found that DDoS attacks that request network connections using larger-than-normal SYN packets have become very popular and now account for more than 51 percent of large-bandwidth attacks. Meanwhile, amplification attacks using the domain name system (DNS) protocol and network time protocol (NTP) account for 35 percent and almost 14 percent of large packet floods, respectively.

In many cases, these attacks are used in conjunction with other types of more subtle denial-of-service attacks. Such multi-vector attacks are more difficult to stop, according to Igal Zeifman, product developer at Incapsula.

"I think that most of the general public thinks of DDoS as a single vector—either a SYN flood or an NTP reflection attack—but 81 percent of events are multi-vector DDoS events," Zeifman said. "Many of the organizations who try to tackle the problem by themselves, and that's OK if they do, will be facing attacks that come from several directions at once."

Only 19 percent of attacks use a single kind of denial-of-service strategy, according to Incapsula's report. More than 41 percent use two vectors, another 32 percent use three vectors, and almost 8 percent use four or more types of DDoS attacks to accomplish their mission, the report stated.

While denial-of-service attacks have had a reputation as an unsophisticated tool for less serious attackers, the techniques have rapidly advanced over the last three years and been incorporated into more sophisticated attacks.

Increasingly, attackers combine a SYN flood attack, which attempts to open a connection with the targeted server and consumes computer resources, and large SYN packets, which overwhelms local bandwidth. Such combination attacks account for about three-quarters of all large DDoS events, according to Incapsula.

Over the past two years, reflection attacks—also known as amplification attacks—using the domain name system protocol have become more popular. The pace of attacks have escalated, however, as cyber-criminals have exploited a flaw in the network time protocol (NTP) to quickly create massive floods of data.

While the NTP attacks have garnered a great deal of attention, they ultimately won't amount to much, Zeifman said.

"It is a known attack. It has been dismissed, because NTP DDoS is very easy to mitigate, especially if you are protecting regular Websites, which are not expected to receive high volumes of NTP requests," he said.

Nearly half of all attacks come from a group of 10 countries, according to Incapsula. Topping the list are India, China and Iran, accounting for 9.6 percent, 9.2 percent and 8 percent of DDoS attacks, respectively, according to the report.

Robert Lemos

Robert Lemos

Robert Lemos is an award-winning freelance journalist who has covered information security, cybercrime and technology's impact on society for almost two decades. A former research engineer, he's...